Implantable medical devices, such as leads, vascular devices, heart valves, annuloplasty rings or bands, or other prosthetic devices, typically undergo in vitro testing and structural modeling to ensure that the device conforms to long-term performance standards. Although mechanical failure of such devices is rare, fracture or other forms of mechanical failure do occur within the implanted environment following repeated deformation due to cardiac or other bodily motion. In vitro tests and structural models are sometimes designed to mimic or exceed the deformations that a device will endure once implanted, these testing methods and structural models have not been motivated by in vivo measurements of actual device deformations.
Numerous systems and algorithms have been proposed or are available for accurate detection of anatomic surfaces in medical images and for visualizing the location of a medical device for surgical navigation. Reference is made, for example, to U.S. Pat. No. 6,119,033 issued to Speigelman et al., U.S. Pat. No. 6,236,875 issued to Bucholz et al, and U.S. Pat. No. 5,983,126 issued to Wittkampf. Algorithms are also available for performing finite element analysis for estimating stress and resultant force distributions along a geometric structure. However, an accurate method for reconstruction of an implanted non-linear medical device, such as a catheter, a stent, or a heart valve device, for example, to measure the repetitive motion and deformation of the implanted device is not available.
A method for dynamic three-dimensional reconstruction of an implanted medical device shape and motion would be valuable in designing and validating physically realistic in vitro mechanical tests and structural models. The inventor of the present invention previously developed an algorithm for non-invasive reconstruction of an initially straight cardiac lead. See Baxter W W, et al., Medical Image Analysis 2001; 5:255-270. However, highly-curved medical devices, such as annuloplasty rings or bands, stents, or catheters, for example cannot be accurately reconstructed assuming a straight or slightly curved configuration. There remains a need therefore, for an algorithm that enables reconstruction of medical devices such as stents, catheters, or heart valve devices having non-linear and highly curved geometries.